The present invention relates to a metal wood golf club head, and more particularly, it relates to a metal wood club head bringing a wood club head of extra-large volume into a compact appearance shape, providing no feeling of misfit also when used by an upper-class person and capable of increasing a carry by remarkably improving restitution characteristics of the metal wood club head.
An example of a conventional golf club head is disclosed in Japanese Patent Laying-Open No. 6-15016, for example. In this gazette, there is disclosed a head prepared by bonding a plastic material or a composite material to a face part of a metal head and rendering it a hitting surface.
Another example of the golf club head is disclosed in Japanese Patent Laying-Open No. 9-192269. In this gazette, there is disclosed a metal wood club head prepared by molding a face part of a metal wood club head in the form of a roll and arranging a sweet spot under the face center of this face part, a head matching the top position of the face part formed in the shape of a roll with the aforementioned sweet spot.
As an item required to a golf club head, it is desired that restitution characteristics of the head is high in order to bring a sufficient carry to the player. In particular, a metal wood club head is used in a middle course or a long course, and a next shot is eased by gaining a carry.
In relation to the metal wood club head described in Japanese Patent Laying-Open No. 6-15016, however, there has been the following problem: That is, although the restitution characteristics increases by bonding the plastic material or the composite material having a small elastic coefficient to the face part, steps are complicated due to occurrence of a molding step of molding the deposit in a fit shape and a bonding step of mounting the deposit. Further, there has been such a problem that separation of a foreign material after hitting takes place.
On the other hand, there has been the following problem also in relation to the metal wood club head described in Japanese Patent Laying-Open No. 9-192269. That is, the position of the center of gravity must be lowered in order to locate the sweet spot under the face center. Therefore, working for mounting a high specific gravity material on the sole or the like is required, and a cost takes place. Further, there has also been such a problem that it is difficult to control the thickness since the head material is deeply drawn for attaining the roll shape.
Accordingly, the inventor has solved the aforementioned problems and come to propose an invention related to a metal wood club head which is a head manufactured by the same system material at a small manufacturing cost and improving restitution characteristics of the head. The same system material mentioned here indicates that including the material itself and an alloy with at least two types of other metals.
A metal wood club head according to the present invention comprises a face part, a back part, a crown part forming an upper portion from the face part to the back part and a sole part forming a lower portion from the face part to the back part, and has a hollow hull structure. The vertical difference between a maximum face part height (MFH) from the sole part and a back part height (BH) from the sole part is at least within 25 mm, the height of the crown part having a width of 30% to 70% of a head width from the sole part is substantially identical to the maximum face part height (MFH) or more than that and the vertical difference between a maximum crown part height (MCH) from the sole part and the maximum face part height (MFH) is at least within 8 mm, and it has set the radius (R1) of curvature of the crown part substantially uniformly within the range of 100 mm to 1000 mm, set the radius (R2) of curvature of the sole part substantially uniformly within the range of 500 mm to 2000 mm, and set the ratio of thicknesses of the crown part and the sole part within the range of 1.0 to 1.2.
It is preferable to set the radius (R3) of curvature of a roll of the aforementioned face part to at least 254 mm and not more than 381 mm, and to set the radius (R4) of curvature of a bulge to at least 254 mm and not more than 381 mm.
The ratio of the maximum face part height (MFH) and a maximum face part width (MFW) is preferably at least 0.5.
The thickness of the face part is preferably at least 1.0 mm and not more than 3.0 mm.
The area of the face part is preferably at least 3300 mm2 and not more than 7500 mm2.
It is preferable to form a bulging zone on a top portion of the crown part from the face part to the back part. The height of this bulging zone is preferably at least 0.1 mm and not more than 4 mm, and the width is preferably at least 10 mm and not more than 20 mm.
The material for the face part is a single metal material, and the face part is preferably molded without performing solution treatment after forging the metal material.